The Gale Encyclopedia of Neurological Disorders vol 2 - part 3 pptx

Acoustic nerve The cranial nerve VIII, involved in both hearing and balance Meninges The three-layered membranous covering of the brain and spinal cord Axillary Referring to the armpit Meningioma A tumor made up of cells of the lining of the brain and spinal cord (meninges) Cataracts Abnormal clouding or opacities within the lens of the eye Gamma-knife surgery A technique of focusing very intense radiation on an extremely well-defined area of abnormal tissue requiring treatment, thus allowing a very high dose of radiation to be used with less damage to neighboring, normal tissue Glial cell A type of cell in the nervous system that provides support for the nerve cells Glioma A tumor made up of abnormal glial cells Inguinal Referring to the groin area Neurofibromas Soft, rubbery, flesh-colored tumors made up of the fibrous substance that covers peripheral nerves Pheochromocytoma A tumor of the adrenal glands that causes high blood pressure Posterior subcapsular lenticular opacity A type of cataract in the eye Rhabdomyosarcoma A tumor of the tendons, muscles, or connective tissue Iris In the eye, the colored ring that is located behind the cornea and in front of the lens Schwann cell Cells that cover the nerve fibers in the body, providing both insulation and increasing the speed of nerve conduction Leukemia Cancer of a blood cell Scoliosis Side-to-side curvature of the spine Lisch nodule A benign growth within the iris of the eye Sphenoid A bone of the skull Macule A small, flat area of abnormal color on the skin dopamine Most often, the drugs involved are those that treat psychosis, called neuroleptic medications The syndrome results in dysfunction of the autonomic nervous system, the branch of the nervous system responsible for regulating such involuntary actions as heart rate, blood pressure, digestion, and sweating Muscle tone, body temperature, and consciousness are also severely affected Description Most cases of neuroleptic malignant syndrome develop between four to 14 days of the initiation of a new drug or an increase in dose However, the syndrome can begin as soon as hours after the first dose or as long as years after medication initiation A variety of factors may increase an individual’s risk of developing this condition, including: • high environmental temperatures • dehydration • agitation or catatonia in a patient • high initial dose or rapid dose increase of neuroleptic, and use of high-potency or intramuscular, long-acting (depot) preparations • simultaneous use of more than one causative agent Tinnitus The abnormal sensation of hearing a ringing or buzzing noise Wilms’ tumor A childhood tumor of the kidneys • sudden discontinuation of medications for Parkinson’s disease • past history of organic brain syndromes, depression, or bipolar disorder • past episode of neuromuscular malignant syndrome (risk of recurrence may be as high as 30%) Because of heightened awareness of this syndrome and improved monitoring for its development, mortality rates have dropped from 20–30% down to 5–11.6% Demographics Neuroleptic malignant syndrome is thought to affect about 0.02–12.2% of all patients using neuroleptic medications Because more men than women take neuroleptic medications, the male-to-female ratio is about 2:1 Causes and symptoms Neuroleptic malignant syndrome occurs due to interference with dopamine activity in the central nervous system, either by depletion of available reserves of dopamine or by blockade of receptors that dopamine usually stimulates GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 599 Neuroleptic malignant syndrome Key Terms Neuroleptic malignant syndrome Neuroleptic malignant syndrome most commonly affects patients who are using neuroleptic or antipsychotic medications, including prochlorperazine (Compazine), promethazine (Phenergan), olanzapine (Zyprexa), clozapine (Clozaril), and risperidone (Risperdal) Other medications that block dopamine may also precipitate the syndrome, including metoclopramide (Reglan), amoxapine (Ascendin), and lithium Too-fast withdrawal of drugs used to treat Parkinson’s disease (levodopa, bromocriptine, and amantadine) can also precipitate neuroleptic malignant syndrome Symptoms of the disorder include: • extremely high body temperature (hyperthermia), ranging from 38.6° to 42.3° C or 101° to 108° F • heavy sweating Treatment must be aggressive Supportive treatment should include hydration with fluids, cooling, and supplemental oxygen Causative medications should be immediately discontinued, and medications that restore dopamine levels (bromocriptine, amantadine) administered Dantrolene can be given to more quickly resolve muscle rigidity and hyperthermia Benzodiazepines, such as lorazepam, may help agitated patients, and may also help relax rigid muscles Benzodiazepines may also aid in the reversal of catatonia In severe or intractable cases of catatonia or psychosis that remains after other symptoms of neuroleptic malignant syndrome have resolved, electroconvulsive therapy may be required Prognosis • fast heart rate (tachydardia) • fast respiratory rate (tachypnea) • rapidly fluctuating blood pressure • impaired consciousness • tremor • rigid, stiff muscles (termed “lead pipe rigidity”) • catatonia (a fixed stuporous state) Without relatively immediate, aggressive treatment, coma and complete respiratory and cardiovascular collapse will take place, followed by death Diagnosis Diagnosis requires a high level of suspicion when characteristic symptoms appear in a patient treated with agents known to cause neuroleptic malignant syndrome The usual diagnostic criteria for neuroleptic malignant syndrome includes the presence of hyperthermia (temperature over 38° C or 101° F) with no other assignable cause, muscle rigidity, and at least five of the following signs or symptoms: impaired mental status, tremor, fast heart rate, fast respiratory rate, loss of bladder or bowel control, fluctuating blood pressure, metabolic acidosis, fluctuating blood pressure, excess blood acidity (metabolic acidosis), increased blood levels of creatanine phosphokinase (normally found in muscles and released into the bloodstream due to muscle damage), heavy sweating, drooling, or increased white blood cell count (leukocytosis) With quick identification of the syndrome and immediate supportive treatment, the majority of patients recover fully, although mortality rates are still significant Signs that may warn of a poor prognosis include temperature over 104° F and kidney failure In patients whose syndrome was precipitated by the use of oral medications, symptoms may last for seven to 10 days In patients whose syndrome was precipitated by the use of long-acting, intramuscular preparation, symptoms may continue as long as 21 days Special concerns Patients with a history of neuroleptic malignant syndrome are also at increased risk for a similar malignant hyperthermia syndrome that is precipitated by the administration of surgical anesthetics Resources BOOKS Saper, Clifford B “Autonomic disorders and their management.” Cecil Textbook of Medicine, edited by Lee Goldman Philadelphia: W B Saunders Company, 2003 Kompoliti, Katie, and Stacy S Horn “Drug-induced and iatrogenic neurological disorders.” Ferri’s Clinical Advisor: Instant Diagnosis and Treatment, edited by Fred F Ferri St Louis: Mosby, 2004 Olson, William H ldquo;Neuroleptic malignant syndrome.” Nelson Textbook of Pediatrics, edited by Richard E Behrman, et al Philadelphia: W B Saunders Company, 2004 WEBSITES Treatment team Neuroleptic malignant syndrome usually requires treatment in an intensive care unit, with appropriate specialists, including intensivists, pulmonologists, cardiologists, psychiatrists 600 Treatment National Institute of Neurological Disorders and Stroke (NINDS) NINDS Neuroleptic Malignant Syndrome Information Page January 23, 2002 (June 4, 2004) GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Neurologist Key Terms Key Terms Autonomic nervous system The divisions of the nervous system that control involuntary functions, such as breathing, heart rate, blood pressure, digestion, glands, smooth muscle Bipolar disorder A psychiatric illness characterized by both recurrent depression and recurrent mania (abnormally high energy, agitation, irritability) Catatonia A fixed, motionless stupor Creatanine phosphokinase A chemical normally found in the muscle fibers, and released into the bloodstream when the muscles undergo damage and breakdown Depot A type of drug preparation and administration that involves the slow, gradual release from an area of the body where the drug has been injected Depression A psychiatric disorder in which the mood is low for a prolonged period of time, and feelings of hopelessness and inadequacy interfere with normal functioning Dopamine A brain neurotransmitter involved in movement ORGANIZATIONS Neuroleptic Malignant Syndrome Information Service PO Box 1069 11 East State Street, Sherburne, NY 13460 (607) 674-7920 or (888) 667-8367; Fax: (607) 674-7910 gillesan@exchange.nih.gov or info@nmsis.org Rosalyn Carson-DeWitt, MD S Neurologist Definition A neurologist is a physician who has undergone additional training to diagnose and treat disorders of the nervous system Description The training a neurologist receives enables the individual to recognize nervous system malfunctions, to accurately diagnose the nature of the dysfunction (such as Hyperthermia Elevated body temperature Leukocytosis An elevated white blood cell count Metabolic acidosis Overly acidic condition of the blood Neuroleptic Referring to a type of drug used to treat psychosis Neurotransmitter A chemical that transmits information in the nervous system Organic brain syndrome A brain disorder that is caused by defective structure or abnormal functioning of the brain Parkinson’s disease A disease caused by deficient dopamine in the brain, and resulting in a progressively severe movement disorder (tremor, weakness, difficulty walking, muscle rigidity, fixed facial expression) Receptor An area on the cell membrane where a specific chemical can bind, in order to either activate or inhibit certain cellular functions Tachycardia Elevated heart rate Tachypnea Elevated breathing rate disease or injury), and to treat the malady While many people associate a neurologist with treating brain injuries, this is just one facet of a neurologist’s responsibility and expertise Diseases of the spinal cord, nerves, and muscles that affect the operation of the nervous system can also be addressed by a neurologist The training that is necessary to become a neurologist begins with the traditional medical background From there, the medical doctor trains for several more years to acquire expertise in the structure, functioning, and repair of the body’s neurological structures, including the area of the brain called the cerebral cortex, and how the various regions of the cortex contribute to the normal and abnormal functioning of the body Typically, a neurologist’s educational path begins with premed studies at a university or college These studies can last up to four years Successful candidates enter medical school Another four years of study is required for a degree as a doctor of medicine (MD) Following completion of the advanced degree, a one-year internship is usually undertaken in internal medicine; sometimes, internships in transitional programs that include pediatrics GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 601 Neuromuscular blockers and emergency-room training are chosen Finally, another training period of at least three years follows in a neurology residency program The latter program provides specialty experience in a hospital and can include research Postdoctoral fellowships lasting one year or more offer additional opportunities for further specialization After completion of the more than decade-long training, medical doctors can become certified as neurologists through the American Board of Psychiatry and Neurology Those with an osteopathy background can be certified through the American Board of Osteopathic Neurologists and Psychiatrists Most neurologists belong to professional organizations such as the American Academy of Neurology (AAN), which is dedicated to setting practice standards, supporting research, providing continuing education, and promoting optimum care for persons with neurological disorders Numerous professional publications specialize in neurology, including Neurology Today, Neurology, Brain, and Archives of Neurology A neurologist can sometimes be a patient’s principle physician This is true when the patient has a neurological problem such as Parkinson’s or Alzheimer’s disease or multiple sclerosis As well, an important aspect of a neurologist’s daily duties is to offer advice to other physicians on how to treat neurological problems A family physician might consult a neurologist when caring for patients with stroke or severe headache When a neurologist examines a patient, details such as vision, physical strength and coordination, reflexes, and sensations like touch and smell are probed to help determine if the medical problem is related to nervous system damage More tests might be done to help determine the exact cause of the problem and how to treat the condition While neurologists can recommend surgery, they not actually perform the surgery That is the domain of the neurosurgeon One well-known neurologist is the English-born physician and writer Oliver Sacks (1933– ) In addition to maintaining a clinical practice, Sacks has authored numerous popular books that describe patients’ experiences with neurological disorders and neurologists’ experiences in treating them Another notable neurologist was Alois Alzheimer (1864–1915) A German neurologist, he first observed and identified the symptoms of what is now known as Alzheimer’s disease Resources BOOKS Bluestein, Bonnie Ellen Preserve Your Love for Science: Life of William A Hammond, American Neurologist Cambridge, UK: Cambridge University Press, 1991 Restak, Richard The Brain Has a Mind of Its Own: Insights from a Practicing Neurologist Three Rivers, MI: Three Rivers Press, 1999 602 Sacks, Oliver The Man Who Mistook His Wife for a Hat: And Other Clinical Tales Carmichael, CA: Touchstone Books, 1998 OTHER “What Is a Neurologist?” Neurology Channel Healthcommunities.com May 6, 2004 (June 2, 2004) ORGANIZATIONS American Board of Psychiatry and Neurology, Inc 500 Lake Cook Road, Suite 335, Deerfield, IL 60015-5249 (847) 945-7900 or (800) 373-1166; Fax: (847) 945-1146 American Academy of Neurology 1080 Montreal Avenue, Saint Paul, MN 55116 (651) 695-2717 or (800) 8791960; Fax: (651) 695-2791 memberservices@aan.com Brian Douglas Hoyle, PhD S Neuromuscular blockers Definition Neuromuscular blocking agents are a class of drugs primarily indicated for use as an adjunct to anesthesia Neuromuscular blocking drugs relax skeletal muscles and induce paralysis Purpose Neuromuscular blockers are indicated for a wide variety of uses in a hospital setting, from surgery to trauma care In surgery, they are used to prepare patients for intubation before being placed on a ventilator and to suppress the patient’s spontaneous breathing once on a ventilator Description Neuromuscular blockers relax skeletal muscle tone by blocking transmission of key neurotransmitters through the neuron receptors at the neuromuscular junction (NMJ) They are divided into two major categories, depolarizing and non-depolarizing neuromuscular blockers, corresponding to the manner in which they exert their therapeutic effect Depolarizing neuromuscular blocking agents mimic the effects of the neurotransmitter acetylcholine (ACh) and change the interaction between ACh and neuron receptors Blockade occurs because membranes surrounding the neuromuscular junction become unresponsive to typical ACh-receptor interaction Non-depolarizing neuromuscular blockers bind to receptors to prevent transmission of impulses through ACh neurotransmitters Neuromuscular blockers are primarily used in a clinical or hospital setting In the United States, they are GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS A physician will decide which neuromuscular blocking agent, or combination of neuromuscular blocker and other type of anesthesia, is appropriate for an individual patient During surgical anesthesia, neuromuscular blockers are administered after the induction of unconsciousness, in order to avoid patient distress at the inability to purposefully move muscles Neuromuscular blockers can be used on pediatric patients Recommended dosage Neuromuscular blocking agents are most often administered though an intravenous (IV) infusion tube Typically, the time in which the medicines begin to exert their effects and duration of action are more predictable when neuromuscular blocking agents are administered via IV Dosages vary depending on the neuromuscular blocking agent used and the duration of action desired The age, weight, and general health of an individual patient can also affect dosing requirements Depolarizing and non-depolarizing agents are grouped together into three categories based on the time in which they begin to exert their anesthetic effects, causing muscle relaxation or paralysis and desensitization, and the duration of those effects (duration of action) Short-acting neuromuscular blockers begin to work within 30 seconds to twoand-a-half minutes and have a typical duration of action ranging from five to twenty minutes Short-acting agents include mivacurium, rocuronium, and succinylcholine Intermediate-acting agents exert their effects within two to five minutes and typically last for twenty to sixty minutes Atracurium, cisatracurium, pancuronium, and vecuronium are intermediate-acting neuromuscular blockers Long-acting neuromuscular blocking agents take effect within twoand-a-half to six minutes and last as long as 75–100 minutes Doxacurium, pipecuronium, and tubocurarine are long-acting neuromuscular blocking agents The duration of action of any neuromuscular blocking agent can be prolonged by administering smaller supplemental (maintenance) doses via IV following the initial blockade-creating dose Precautions Each neuromuscular blocking agent has its own particular precautions, contraindications, and side effects However, many are common to all neuromuscular blockers Neuromuscular blocking agents may not be suitable for persons with a history of lung diseases, stroke, increased intracranial pressure, increased intraocular (within the eye) pressure as in glaucoma, liver or kidney disease, decreased renal function, diseases or disorders affecting the muscles, angina (chest pain), and irregular heartbeats and other heart problems Neuromuscular blockers are not typically used on patients with recent, severe burns, elevated potassium levels, or severe muscle trauma There is an increased risk of seizure in patients with seizure disorders such as epilepsy Neuromuscular blockers can be administered to patients who have suffered a spinal cord injury resulting in paraplegia (paralysis) immediately following the injury But further use of neuromuscular blockers is typically avoided 10–100 days after the initial trauma Patients who are obese or have increased plasma cholinesterase activity may exhibit increased resistance to neuromuscular blocking agents Some cholinergic stimulants that act as cholinesterase inhibitors, including medications used in the treatment of Alzheimer’s disease, may enhance neuromuscular blockade and prolong the duration of action of neuromuscular blockers With careful supervision, neuromuscular blocking agents can be used in pediatric patients However, rare but serious complications such as bradycardia (decreased heart rate) are more likely to develop in children than in adults Placental transfer (passing of the medication to the fetus) of neuromuscular blocking agents is minimal Histamine release is associated with neuromuscular blocking agents tubocurare and succinylcholine Complications such as bronchospasm, decreased blood pressure, and blood clotting problems could arise in patients especially sensitive or susceptible to changes in histamine levels Side effects In some patients, neuromuscular blockers may produce mild or moderate side effects Anesthesiologists (specialists in administering anesthesia and treating pain) may notice a slight red flushing of the face as neuromuscular blockers are administered to the patient After completion of the surgical procedure, headache, nausea, muscle soreness, and muscle weakness are the most frequently reported side effects attributed to neuromuscular blockers Most of these side effects disappear or occur less frequently after a few hours or days With depolarizing neuromuscular blocking agents, fasciculations (involuntary muscle contractions) may occur before the onset of muscle relaxation or paralysis Some patients report generalized muscle soreness or pain after taking a neuromuscular blocking agent that causes fasciculations Women and middle-aged patients reported this side effect more frequently GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 603 Neuromuscular blockers known by several generic and brand names, including atracurium (Tracurium), cisatracurium (Nimbex), doxacurium (Neuromax), mivacurium (Mivacron), pancuronium (Pavulon), pipecuronium (Arduan), rocuronium (Zemeron), succinylcholine (Anectine), tubocurarine, and vecuronium (Norcuron) Neuronal migration disorders PERIODICALS Key Terms Acetylcholine The neurotransmitter, or chemical that works in the brain to transmit nerve signals, involved in regulating muscles, memory, mood, and sleep Hunter, Jennifer M “New Neuromuscular Blocking Drugs.” New England Journal of Medicine 332, no 25 (1995): 1691–1699 Adrienne Wilmoth Lerner Neuromyelitis optica see Devic syndrome Fasciculations Fine tremors of the muscles Neuromuscular junction The junction between a nerve fiber and the muscle it supplies Neurotransmitter Chemicals that allow the movement of information from one neuron across the gap between the adjacent neuron Other, uncommon side effects or complications associated with neuromuscular blockers can be serious or may indicate an allergic reaction As neuromuscular blockers are most frequently used in trauma, surgical, and intensive hospital care, physicians may be able to counteract the following side effects or complications as they occur: • bradycardia • cessation of breathing • severe bronchospasm • prolonged numbness in the extremities • extended paralysis • jaw rigidity • skeletal muscle atrophy or trauma • impaired blood clotting Neuronal ceroid lipofuscinosis see Batten disease S Neuronal migration disorders Definition Neuronal migration disorders are a diverse group of congenital brain abnormalities that arise specifically from defective formation of the central nervous system During early brain development, neurons are born and move over large distances to reach their targets and thereby give rise to the different parts of the brain The control of this process is highly orchestrated and dependent on the expression of various environmental and genetic factors that continue to be discovered in genetic studies of mice and humans The critical role neuronal migration plays in brain development is evident from the variety of gross malformations that can occur when it goes wrong Defective neuronal migration leads to a broad range of clinical syndromes, and most affected patients will have a combination of mental retardation and epilepsy • severe decrease in blood pressure • chest pain or irregular heartbeat Description Interactions Neuromuscular blocking agents may have negative interactions with some anticoagulants, anticonvulsants (especially those also indicated for use as skeletal muscle relaxants), antihistamines, antidepressants, antibiotics, pain killers (including non-prescription medications) and monoamine oxidase inhibitors (MAOIs) Cholinergic stimulants, some insecticides, diuretics (furosemide), local anesthetics, magnesium, antidepressants, anticonvulsants, aminoglycoside antibiotics, high estrogen levels, and metoclopramide (Reglan) may affect the duration of action of neuromuscular blocking agents Resources BOOKS Omoigui, Erowid The Anesthesia Drugs Handbook St Louis: Mosby, 1995 604 Neuronal migration disorders include lissencephaly as part of the agyria-pachygyria-band spectrum, cobblestone lissencephaly, periventricular heterotopia, and other variants such as Zellweger and Kallman syndrome Patients may have only focal collections of abnormally located neurons known as heterotopias The common factor in these disorders is a defect in neuronal migration, a key process in brain development that occurs during weeks 12 to 16 of gestation Some disorders such as polymicrogyria and schizencephaly are presumably due to abnormal neuronal migration due to studies showing heterotopias in other parts of the brain, but the exact relationship is unclear Early in brain development, neurons are born in specific locations in the brain and migrate to their final destinations to create distinct brain regions Each step of this process, from starting, continuing, and stopping migration, is controlled by distinct molecular mechanisms that are regulated by the activity of genes Defects in these GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Lissencephaly Lissencephaly is the most extreme example of defective neuronal migration In lissencephaly or agyria, neuronal migration fails globally, causing the brain to appear completely smooth and have abnormal layering in the cortex Various genes have been associated with varying levels of severity of lissencephaly giving rise to a spectrum of disorders ranging from classical lissencephaly to milder forms such as double cortex syndrome or pachygyria Classical or type I lissencephaly differs from type II or cobblestone lissencephaly In cobblestone lissencephaly, the defect is presumably an overmigration of neurons past their targets, giving rise to the abnormally bumpy surface Periventricular heterotopia Periventricular heterotopia is a disorder where neurons fail to begin the process of migration Neurons are generated near the ventricular zone but not start the process of migration to their destinations Instead, they are stuck and collect around the ventricles, giving rise to the distinct appearance on brain imaging Other neuronal migration disorders Zellweger syndrome is a disorder of neuronal migration that may consist of abnormally large folds (pachygyria) and heterotopias spread throughout the brain It is thought to be due to a defect in peroxisome metabolism, a pathway by which cells break down waste products The relationship between this metabolic defect and neuronal migration is unclear at this time Kallman syndrome is a disorder where cells fail to migrate to the portion of the brain controlling smell as well as the hypothalamus, a region that controls hormone secretion The mechanism underlying this disease is unclear Schizencephaly is grouped as a neuronal migration disorder although the exact etiology is unknown Schizencephaly is an example of abnormal neuronal migration that may occur locally rather than globally In schizencephaly, an early insult to the brain in the form of an infection, stroke, or genetic defect leads to abnormal migration of neurons in a portion of the brain and subsequent lack of developed brain tissue, giving rise to the characteristic brain clefts that define this syndrome Schizencephaly may show a wide range of presentations, with bilateral clefts that vary in size and extent of involvement Polymicrogyria refers to an abnormal amount of small convolutions (gyri) in affected areas of the cerebral cortex and is believed to be a neuronal migration disorder, although the exact etiology is unknown Demographics Neuronal migration disorders are rare overall, but the exact incidence is unknown Patients may have very mild degrees of the different disorders and may not be diagnosed if they not manifest symptoms, making the actual incidence difficult to determine Causes and symptoms The majority of neuronal migration disorders seen in clinical practice are thought to be genetic in cause Much of what is known about neuronal migration disorders to date has been discovered from intense research identifying the genes affected in individuals with these diseases The widespread abnormal expression of defective genes leads to the global nature of the disorders, contrary to acquired developmental brain insults, which lead to more localized defects Several genes have been implicated in causing the various disorders, and they continue to be identified The most well characterized genes include DCX on the X chromosome, responsible for double cortex syndrome, and LIS1 on chromosome 17, the first gene identified for lissencephaly Cobblestone lissencephaly is associated with abnormalities in fukutin, a gene responsible for Fukuyama muscular dystrophy, a syndrome consisting of muscle weakness and cobblestone lissencephaly Periventricular heterotopia is associated with abnormalities of the filamin1 gene on the X chromosome DCX, LIS1, and filamin1 are genes responsible for controlling the mechanics of cell movement during neuronal migration Schizencephaly has been associated with abnormalities in EMX2, a transcription factor gene whose role in neuronal migration is as yet unidentified Neuronal migration disorders can also be associated with early insults to the brain from infections or damage from stroke Most neuronal migration disorders present with some combination of epilepsy, mental retardation, and abnormalities in head size, known as microcephaly Some patients, such as those with small heterotopias, may have no symptoms at all since the severity of the defect is very mild Patients may also have cerebral palsy or abnormalities in muscle tone Depending on the severity of the malformation, the level of mental retardation may vary from mild to severe Patients with lissencephaly are usually severely delayed, have failure to thrive, and are microcephalic They may also have accompanying eye problems Patients with double cortex syndrome or schizencephaly may have milder symptoms and may only present with seizures Schizencephaly may have associated complications of increased fluid pressure in the brain, known as hydrocephalus Periventricular heterotopia and polymicrogyria may present with only seizures Some neuronal migration disorders such as lissencephaly may be GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 605 Neuronal migration disorders genes lead to the various presentations of neuronal migration disorders seen in clinical practice Neuronal migration disorders part of a larger syndrome affecting other body parts such as the muscle, eyes, or face Diagnosis Diagnosis is usually made by neuroimaging CT scan or MRI of the brain will show the characteristic abnormality MRI has better resolution and may detect polymicrogyria or small heterotopias more easily than CT Genetic testing is available for patients with lissencephaly to identify whether the DCX or LIS1 gene is defective Knowledge of the genes affected allows for counseling and family planning Laboratory tests are not useful in diagnosis Prognosis There is no known cure for any of the neuronal migration disorders Due to the congenital nature of the diseases, the symptoms tend to be static and not improve The prognosis varies for each individual depending on the extent of the defect and the accompanying neurologic deficits Most individuals with severe malformations such as classical lissencephaly or bilateral schizencephaly will die at an early age due to failure to thrive or infections such as pneumonia Their cognitive development stays at the three month level Patients with milder forms such as unilateral schizencephaly, periventricular heterotopia, or subcortical band heterotopia may have mild mental retardation and seizures only and live a normal life span Treatment team Management of neuronal migration disorders involves a pediatrician, pediatric neurologist and physical therapists With symptoms of later onset, an adult neurologist may be involved in treating symptoms of seizures Rehabilitation specialists may help in prescribing medications for cerebral palsy or increased muscle tone A case manager may be involved in coordinating care and resources Special concerns Educational and Social Needs Due to developmental disability, children with neuronal migration disorders who survive beyond the age of two may benefit from special education programs Various state and federal programs are available to help individuals and their families with meeting these needs Resources Treatment There are no known cures for the various neuronal migration disorders at this time The majority of treatments are directed towards symptoms caused by the malformed brain Seizures may be treated with anticonvulsant medications Refractory seizures may respond to neurosurgical removal of abnormal brain tissue Neurosurgery may be required to relieve hydrocephalus, by placement of a shunt Increased muscle tone may respond to injections of botulinum toxin or muscle relaxants Patients may require feeding through a tube due to inability to swallow normally Recovery and rehabilitation Due to the congenital nature of neuronal migration disorders, most patients not recover from their symptoms The course of disease tends to be static Physical and occupational therapists may help treat symptoms of weakness or increased tone that limit mobility and daily hand use BOOKS “Congenital Anomalies of the Nervous System.” In Nelson Textbook of Pediatrics, 17th edition, edited by Richard E Behrman, Robert M Kliegman, and Hal B Jenson Philadelphia, PA: Saunders 2004 Menkes, John H., and Harvey Sarnat, eds Childhood Neurology, 6th edition Philadelphia: Lippincott Williams & Wilkins, 2000 PERIODICALS Gleeson, J G “Neuronal Migration Disorders.” Mental Retardation and Developmental Disabilities Research Reviews (2001): 167–171 Guerrini, R., and R Carrozzo “Epilepsy and Genetic Malformations of the Cerebral Cortex.” American Journal of Medical Genetics 106 (2001): 160–173 Kato, M., and W B Dobyns “Lissencephaly and the molecular basis of neuronal migration.” Human Molecular Genetics 12 (2003): R89–R96 Ross, M E., and C A Walsh “Human Brain Malformations and Their Lessons for Neuronal Migration.” Annual Review of Neuroscience 24 (2001): 1041–1070 WEBSITES Clinical trials A clinical trial is currently under way and is funded by the National Institutes of Health to identify genes responsible for neuronal migration disorders such as lissencephaly and schizencephaly For contact information for the Walsh Lab Site, see Resources below 606 Cephalic Disorders Information Page National Institutes of Neurological Disorders and Stroke (NINDS) ORGANIZATIONS March of Dimes Birth Defects Foundation 1275 Mamaroneck Avenue, White Plains, NY 10605 (914) 428-7100 or GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Peter T Lin, MD S Neuropathologist Key Terms Biopsy The surgical removal and microscopic examination of living tissue for diagnostic purposes or to follow the course of a disease Most commonly the term refers to the collection and analysis of tissue from a suspected tumor to establish malignancy Histology The study of tissue structure Definition A pathologist is a medical doctor who is specialized in the study and diagnosis of the changes that are produced in the body by various diseases A neuropathologist is a specialized pathologist who is concerned with diseases of the central nervous system (the brain and spinal cord) Often a neuropathologist is concerned with the diagnosis of brain tumors A neuropathologist is also an expert in the various aspects of diseases of the nervous system and skeletal muscles This range of disease includes degenerative diseases, infections, metabolic disorders, immunologic disorders, disorders of blood vessels, and physical injury A neuropathologist functions as the primary consultant to neurologists and neurosurgeons Description A neuropathologist is a medical doctor who has pursued specialized training Aspects of this training include neurology, anatomy, cell biology, and biochemistry Typically, a patient will not see a neuropathologist Rather, the specialist works in the background, in the setting of the laboratory, to assist in the patient’s diagnosis In the path that leads to the diagnosis of a tumor, disease, or other malady, a neuropathologist typically becomes involved at the request of a neurologist It is the neurologist who suspects a problem or seeks to confirm the presence of a tumor, based on tests such as magnetic resonance imaging (MRI) or a computed assisted tomography (CAT) scan The neurologist can obtain some of the tissue of concern in a procedure known as a biopsy, as well as obtaining fluid or cell samples It is this material that is sent to the pathology lab where the neuropathologist seeks to identify the nature of the problem The diagnosis of brain and spinal cord related damage often involves a visual look at the samples using the extremely high magnification of the electron microscope The neuropathologist can assess from the appearance of the sample whether the sample is unaffected or damaged For example, in brain tissue obtained from a patient with suspected Alzheimer disease, the neuropathologist will look for evidence of the presence of amyloid plaques, which are caused by abnormal folding of protein As well, the neuropathologist will look for other diagnostic signs that support or not support the suspected malady In the case of a tumor, part of a neuropathologist’s responsibility is to identify the tumor and grade it as malignant or benign This is no small task, as there are literally hundreds of different types of tumors The correct identification greatly aids the subsequent treatment process and the patient’s prognosis The neuropathological analysis of a tumor is concerned mainly with two areas The first is the origin of the tumor in the brain Determining the tumor’s origin aids in naming the tumor Secondly, the neuropathologist determines if the tumor displays signs of rapid growth The speed of growth of the tumor can be quantified as a grade A result such as “grade three astrocytoma” is very informative to the neurologist Even if the neuropathologist determines that a brain or spinal cord tumor is benign, the location of the tumor may still pose serious health risks, and this important determination is also usually made by the neuropathologist Another important tool that a neuropathologist uses to examine tissue samples is histology The treatment of a thin section of a sample with specific compounds that will bind to and highlight (stain) regions of interest in the specimen allows the neuropathologist to determine if the stained regions are normal or abnormal in character The histological stains can be applied to a section that has been sliced from the sample at room temperature or at a very low temperature The use of frozen sections can help preserve structural detail in the specimen that might otherwise be changed at a higher temperature The assessment of a stained specimen by the neuropathologist is typically done by examining the material using a light microscope This type of microscope does not magnify the specimen nearly as much as does the electron microscope But such high-power magnification is not necessary to detect the cellular changes in the stained specimen By carefully selecting the stain regimen, a GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 607 Neuropathologist (888) 663-4637; Fax: (914) 428-8203 askus@ marchofdimes.com Neuropsychological testing skilled neuropathologist can reveal much detail about a specimen Histological examinations can also be done much more quickly and easily than electron microscopic examinations Saving time can be important in diagnosis and treatment, especially when dealing with brain tumors Finally, one of the consultative duties of a neuropathologist can also include legal testimony Their expert knowledge can be useful in court cases in which the mental state or functional ability of a person is an important consideration Resources BOOKS Nelson, James S Principles and Practice of Neuropathology New York: Oxford University Press, 2003 OTHER Department of Neurology, University of Debrecen, Hungary Neuroanatomy and Neuropathology on the Internet (February 10, 2004) ORGANIZATIONS American Association of Neuropathologists (AANP) 2085 Adelbert Rd., Cleveland, OH 44106 (216) 368–2488; Fax: (216) 368–8964 aanp@cwru.edu Brian Douglas Hoyle, PhD Neuropathy, hereditary see Charcot-MarieTooth disorder S Neuropsychological testing Definition Clinical neuropsychology is a field with historical origins in both psychology and neurology The primary activity of neuropsychologists is assessment of brain functioning through structured and systematic behavioral observation Neuropsychological tests are designed to examine a variety of cognitive abilities, including speed of information processing, attention, memory, language, and executive functions, which are necessary for goal-directed behavior By testing a range of cognitive abilities and examining patterns of performance in different cognitive areas, neuropsychologists can make inferences about underlying brain function Neuropsychological testing is an important component of the assessment and treatment of traumatic brain injury, dementia, neurological conditions, and psychiatric disorders Neuropsychological testing is also an important tool for examining the effects of 608 toxic substances and medical conditions on brain functioning Description As early as the seventeenth century, scientists theorized about associations between regions of the brain and specific functions The French philosopher Descartes believed the human soul could be localized to a specific brain structure, the pineal gland In the eighteenth century, Franz Gall advocated the theory that specific mental qualities such as spirituality or aggression were governed by discrete parts of the brain In contrast, Pierre Flourens contended that the brain was an integrated system that governed cognitive functioning in a holistic manner Later discoveries indicated that brain function is both localized and integrated Paul Broca and Karl Wernicke furthered understanding of localization and integration of function when they reported the loss of language abilities in patients with lesions to two regions in the left hemisphere of the brain The modern field of neuropsychology emerged in the twentieth century, combining theories based on anatomical observations of neurology with the techniques of psychology, including objective observation of behavior and the use of statistical analysis to differentiate functional abilities and define impairment The famous Soviet neuropsychologist Alexander Luria played a major role in defining neuropsychology as it is practiced today Luria formulated two principle goals of neuropsychology: to localize brain lesions and analyze psychological activities arising from brain function through behavioral observation American neuropsychologist Ralph Reitan emphasized the importance of using standardized psychometric tests to guide systematic observations of brain-behavior relationships Before the introduction of neuroimaging techniques like the computed tomography (CAT or CT) scan and magnetic resonance imaging (MRI), the primary focus of neuropsychology was diagnosis Since clinicians lacked non-surgical methods for directly observing brain lesions or structural abnormalities in living patients, neuropsychological testing was the only way to determine which part of the brain was affected in a given patient Neuropsychological tests can identify syndromes associated with problems in a particular area of the brain For instance, a patient who performs well on tests of attention, memory, and language, but poorly on tests that require visual spatial skills such as copying a complex geometric figure or making designs with colored blocks, may have dysfunction in the right parietal lobe, the region of the brain involved in complex processing of visual information When a patient complains of problems with verbal communication after a stroke, separate tests that examine GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Pain Key Terms Adjuvant A medication or other substance given to aid another drug, such as a tranquilizer given to ease the anxiety of a cancer patient in addition to an analgesic for pain relief Analgesic A medication that relieves pain without causing loss of consciousness Over-the-counter analgesics include aspirin and nonsteroidal antiinflammatory drugs (NSAIDs) Bursa (plural, bursae) A fluid-filled sac or pouch located in joints or other pressure points between tendons and bones Inflammation of a bursa is known as bursitis Capsaicin An alkaloid derived from hot peppers that can be used as a topical anesthetic Dorsal horn The part of the spinal cord that receives and processes pain messages from the peripheral nervous system Endorphins Neuropeptides produced by the body that are released in response to stress or injury and act as natural analgesics Enkephalins Polypeptides that serve as neurotransmitters and short-acting pain relievers Enkephalins also influence a person’s perception of painful sensations Eudynia The medical term for acute pain, or pain that is a symptom of an underlying disease or disorder Limbic system A group of structures found in the brains of all mammals that are associated with emotions, behavior, and such body functions as appetite and temperature regulation • severity • timing (time of day; continuous or intermittent) • location in the body • quality (piercing, burning, aching, etc.) • factors that relieve the pain or make it worse (temperature or humidity; body position or level of activity; foods or medications; emotional stress, etc.) • its relationship to mood swings, anxiety, or depression The doctor will then take the patient’s medical history, including past illnesses, injuries, and operations as well as a family history In some cases, the doctor may need to ask about experiences of emotional, physical, or sexual abuse The doctor will also make a list of all the medications that the patient takes on a regular basis Other 636 Maldynia The medical term for chronic pain, or pain that has become a disease in and of itself as a result of changes in the patient’s nervous system Malingering Knowingly pretending to be physically or mentally ill in order to get out of some unpleasant duty or responsibility, or for economic benefit Narcotic Another term for opioid drugs that refers to their ability to produce drowsiness as well as relieve pain Neurotransmitter Any of a group of chemicals that transmit nerve impulses across the gap (synapse) between two nerve cells Nociceptor A specialized type of nerve cell that senses pain Opioid Any of a number of pain-relieving drugs derived from the opium poppy or from synthetic compounds that have the same effect as natural opioids Pain medicine The medical specialty that deals with the study and prevention of pain, and with the evaluation, treatment, and rehabilitation of patients with acute or chronic pain Somatoform disorders A group of psychiatric disorders in the DSM-IV classification that are characterized by external physical symptoms or complaints related to psychological problems rather than organic illness Thalamus An egg-shaped structure in the brain that integrates pain sensations and other sensory impulses, and relays them to other regions of the brain information that may help the doctor evaluate the pain includes the patient’s occupation and level of functioning at work; marriage and family relationships; social contacts and hobbies; and whether the patient is involved in a lawsuit for injury or seeking workers’ compensation This information may be helpful in understanding what the patient means by “pain” as well as what may have caused the pain, particularly because many people find it easier to discuss physical pain than anxiety, anger, depression, or sexual problems Some doctors may give the patient a brief written pain questionnaire to fill out in the office There are a number of different instruments of this type, some of which are designed to measure pain associated with cancer, arthritis, HIV infection, or other specific diseases Most of these rating questionnaires ask the patient to mark their pain GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Physical examination A thorough physical examination is essential in identifying the specific disorders or injuries that are causing the pain The most important part of pain management is removing the underlying cause(s) whenever possible, even when there is a psychological component to the pain Special tests Although there are no laboratory tests or imaging studies that can demonstrate the existence of pain as such or measure its intensity directly, the doctor may order special tests to help determine the cause(s) of the pain These studies may include one or more of the following: • Imaging studies, usually x rays or magnetic resonance imagings (MRIs) These studies can detect abnormalities in the structure of bones or joints, and differentiate between healthy and diseased tissues • Neurological tests These tests evaluate the patient’s movement, gait, reflexes, coordination, balance, and sensory perception • Electrodiagnostic tests These tests include electromyography (EMG), nerve conduction studies, and evoked potential (EP) tests In EMG, the doctor inserts thin needles in specific muscles and observes the electrical signals that are displayed on a screen This test helps to pinpoint which muscles and nerves are affected by pain Nerve conduction studies are done to determine whether specific nerves have been damaged The doctor positions two sets of electrodes on the patient’s skin over the muscles in the affected area One set of electrodes stimulates the nerves supplying that muscle by delivering a mild electrical shock; the other set records the nerve’s electrical signals on a machine EP tests measure the speed of transmission of nerve impulses to the brain by using two electrodes, one attached to the patient’s arm or leg and the other to the scalp • Thermography This is an imaging technique that uses infrared scanning devices to convert changes in skin temperature into electrical impulses that can be displayed as different colors on a computer monitor Pain related to inflammation, nerve damage, or abnormalities in skin blood flow can be effectively evaluated by thermography • Psychological tests Such instruments as the Minnesota Multiphasic Personality Inventory (MMPI) may be helpful in assessing hypochondriasis and other personality traits related to psychogenic pain Treatment Treatment of either acute or chronic pain may involve several different approaches to therapy Medications Medications to relieve pain are known as analgesics Aspirin and other nonsteroidal anti-inflammatory drugs, or NSAIDs, are commonly used analgesics NSAIDs include such medications as ibuprofen (Motrin, Advil), ketoprofen (Orudis), diclofenac (Voltaren, Cataflam), naproxen (Aleve, Naprosyn), and nabumetone (Relafen) These medications are effective in treating mild or moderate pain A newer group of NSAIDs, which are sometimes called “superaspirins” because they can be given in higher doses than aspirin without causing stomach upset or bleeding, are known as COX-2 inhibitors The COX-2 inhibitors include celecoxib (Celebrex), rofecoxib (Vioxx), and valdecoxib (Bextra) For more severe pain, the doctor may prescribe an NSAID combined with an opioid, usually codeine or hydrocodone Opioids, which are also called narcotics, are strong painkillers derived either from the opium poppy Papaver somniferum or from synthetic compounds that have similar effects Opioids include such drugs as codeine, fentanyl (Duragesic), hydromorphone (Dilaudid), meperidine (Demerol), morphine, oxycodone (OxyContin), and propoxyphene (Darvon) They are defined as Schedule II controlled substances by the Controlled Substances Act of 1970, which means that they have a high potential for abuse in addition to legitimate medical uses A doctor must have a special license in order to prescribe opioids In addition to the risk of abuse, opioids cause potentially serious side effects in some patients, including cognitive impairment (more common in the elderly), disorientation, constipation, nausea, heavy sweating, and skin rashes If the patient’s pain is severe and persistent, the doctor will give separate dosages of opioids and NSAIDs in order to minimize the risk of side effects from high doses of aspirin or acetaminophen In addition, the doctor may prescribe opioids that are stronger than codeine—usually morphine, fentanyl, or levorphanol The “WHO Ladder” for the treatment of cancer pain is based on the three levels of analgesic medication Patients with mild pain from cancer are given nonopioid medications with or without an adjuvant (helping) medication For example, the doctor may prescribe a tranquilizer to relieve the patient’s anxiety as well as the pain medication Patients on the second “step” of the ladder are given a milder opioid and a nonopioid analgesic with or without an adjuvant drug Patients with severe cancer pain are given stronger opioids at higher dosage levels with or without an adjuvant drug GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 637 Pain level on a scale from zero to 10 or zero to 100 with zero representing “no pain” and the higher number representing “worst pain imaginable” or “unbearable pain.” The patient then answers a few multiple-choice questions regarding the impact of the pain on his or her employment, relationships, and overall quality of life Pain Acute pain following surgery is usually managed with opioid medications, most commonly morphine sulfate (Astromorph, Duramorph) or meperidine (Demerol) In some cases, NSAIDs that are available in injectable form (such as ketorolac) are also used Patient-controlled analgesia, or PCA, allows patients to control the timing and amount of pain medication they receive Although there are oral forms of PCA, the most common form of administration involves an infusion pump that delivers a small dose of medication through an intravenous line when the patient pushes a button The PCA pump is preprogrammed to deliver no more than an hourly maximum amount of the drug Some types of chronic pain are treated by injections in specific areas of the body rather than by drugs administered by mouth or intravenously There are three basic categories of injections for pain management: • Joint injections Joint injections are given to treat chronic pain associated with arthritis The most common medications used are corticosteroids, which suppress inflammation in arthritic joints, and hyaluronic acid, which is a compound found in the joint fluid of healthy joints • Soft tissue injections These are given to reduce pain in trigger points (areas of muscle that are hypersensitive to touch) and bursae, which are small pouches or sacs containing tissue fluid that cushions pressure points between tendons and bones When a bursa becomes inflamed—a condition called bursitis—the person experiences pain in the nearby joint Corticosteroids are the drugs most often used in soft tissue injections, although the doctor may also inject an anesthetic into a trigger point in order to relax the muscle • Nerve blocks Nerve blocks are injections of anesthetic around the fibers of a nerve to prevent pain messages relayed along the nerve from reaching the brain They may be used to relieve pain in specific parts of the body for a short period; a common example of this type of nerve block is the lidocaine injections given by dentists before drilling or extracting a tooth Some nerve blocks are injected in or near the spinal column to control pain that affects a larger area of the body; an example is the epidural injection given to women in labor or to patients with sciatica A third type of nerve block is administered to block the sympathetic nervous system as part of pain management in patients with complex chronic pain syndromes Medications used to treat neuropathic pain include tricyclic antidepressants, anticonvulsant medications, selective serotonin reuptake inhibitors, topical creams containing capsaicin or 5% lidocaine, and diphenhydramine (Benadryl) 638 Surgery Because surgery is itself a cause of pain, few surgical treatments to relieve pain were available prior to the discovery of safe general anesthetics in the mid-nineteenth century For most of human history, doctors were limited to procedures that could be completed within two to three minutes because the patients could not bear the pain of the operation Ancient Egyptian doctors gave their patients wine mixed with opium, while early European doctors made their patients drunk with brandy, tied them to the benches that served as operating tables, or put pressure on a nerve or artery to numb a specific part of the body Modern surgeons, however, can perform a variety of procedures to relieve either acute or chronic pain, depending on its cause These procedures include: • removal of diseased or dead tissue to prevent infection • removal of cancerous tissue to prevent the spread of the cancer and relieve pressure on nearby healthy organs and tissues • correction or reconstruction of malformed or damaged bones • insertion of artificial joints or other body parts to replace damaged structures • organ transplantation • insertion of pacemakers and other electrical devices that improve the functioning of damaged organs or help to control pain directly • cutting or destroying damaged nerves to control neuropathic pain PSYCHOTHERAPY Psychotherapy may be helpful to patients with chronic pain syndromes by exploring the connections between anger, depression, or anxiety and physical pain sensations One type of psychotherapy that has been shown to be effective is cognitive restructuring, an approach that teaches people to “reframe” the problems in their lives—that is, to change their conscious attitudes and responses to these stressors Some psychotherapists teach relaxation techniques, biofeedback, or other approaches to stress management as well as cognitive restructuring Another type of psychotherapy that is effective in treating some patients with chronic pain is hypnosis Although there is some disagreement among researchers as to whether hypnosis works by distracting the patient’s attention from painful sensations or whether it works by stimulating the release of endorphins (chemicals produced by the body that are released in response to stress or injury and act as natural analgesics), it has been approved by the American Medical Association since 1958 as a treatment for pain Some therapists offer instruction in self-hypnosis to patients with chronic pain GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS ment include: • Acupuncture Studies funded by the National Center for Complementary and Alternative Medicine (NCCAM) since 1998 have found that acupuncture is an effective treatment for chronic pain in many patients It is thought that acupuncture works by stimulating the release of endorphins, the body’s natural painkillers • Exercise Physical exercise stimulates the body to produce endorphins • Yoga Practiced under a doctor’s supervision, yoga helps to maintain flexibility and range of motion in joints and muscles The breathing exercises that are part of a yoga practice also relax the body • Prayer and meditation The act of prayer by itself helps many people to relax In addition, prayer and meditation are ways to refocus one’s attention and keep pain from becoming the center of one’s life • Naturopathy Naturopaths include dietary advice and nutritional therapy in their treatment, which is effective for some patients suffering from chronic pain syndromes • Hydrotherapy Warm whirlpool baths ease muscular and joint pain • Music therapy Music therapy may involve listening to music, making music, or both Some researchers think that music works to relieve pain by temporarily blocking the “gates” of pain in the dorsal horn of the spinal cord, while others believe that music stimulates the release of endorphins Pain management Pain management refers to a set of skills and techniques for coping with chronic pain The goal of pain management is not complete elimination of pain; rather, the patient learns to keep the pain at a level that he or she can tolerate, and to make the most of life in spite of the pain The American Chronic Pain Association (ACPA) lists seven coping skills that help in managing pain: • not dwelling on physical pain symptoms • emphasizing abilities rather than disabilities • recognizing one’s feelings about the pain and discussing them freely • using relaxation exercises to ease the emotional tension that makes pain worse • doing mild stretching exercises every day (with medical approval) • setting realistic goals for improvement and evaluating them on a weekly basis • affirming one’s basic rights: the right to make mistakes, the right to say no, and the right to ask questions An important part of pain management is participation in a multidisciplinary pain program Many hospitals and rehabilitation centers in the United States and Canada offer pain management programs Ideally, the program will have its own unit apart from patient care areas Good pain management programs offer comprehensive treatment that includes relaxation training and stress management techniques; group therapy, family therapy, personal counseling, and job retraining; physical therapy, including exercise and body mechanics; patient education regarding medications and other aspects of pain management; and aftercare or follow-up support The treatment team in a pain management program is usually headed by a neurologist, psychiatrist, or anesthesiologist with specialized training in pain management Other members of the team include registered nurses, psychiatrists or psychologists, physical and occupational therapists, massage therapists, family therapists, and vocational counselors Clinical trials As of December 2003, the National Institutes of Health (NIH) was sponsoring 35 studies related to various chronic pain conditions and the effectiveness of such treatments as acupuncture, hypnosis, yoga, COX-2 inhibitors, and several experimental drugs Special concerns Pain management in special populations Pain management in the elderly and in children poses additional challenges Although 20% of adults over 65 take an analgesic on a regular basis, older people are more vulnerable to the drug’s side effects, particularly the nausea and bleeding that sometimes results from long-term use of NSAIDs Children require special attention because they not have an adult’s ability to describe their pain New tools have been developed since the mid-1990s to measure pain in children and to help doctors understand their nonverbal cues Addiction and withdrawal Doctors have debated the risk of opioid abuse for most of the past century For many years, patients with severe chronic pain were not given enough of the drugs they needed to control their pain because of the fear that they would become addicted to the narcotics In the mid-1980s, however, some experts in pain management argued that the risk of addiction was quite low, whether the patients suffered from cancer pain or from chronic pain unrelated to cancer As a result, some synthetic narcotics—most notably oxycodone (OxyContin)—were widely prescribed GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 639 Pain COMPLEMENTARY AND ALTERNATIVE (CAM) APPROACHES CAM therapies that are used in pain manage- Pallidotomy and a growing number of patients became addicted to these drugs As of 2003, researchers estimate that 3–14% of the population may have an underlying undiagnosed vulnerability to abuse these substances In addition to the risk of abuse, there is a risk of withdrawal symptoms and a temporary increase in pain (known as rebound pain) if opioid medications are discontinued suddenly Withdrawal symptoms include diarrhea, runny nose and watery eyes, restlessness, insomnia, anxiety, nausea, and abdominal cramps These symptoms are usually treated with clonidine (Catapres), an antihypertensive drug, and NSAIDs or antihistamines The various risks of long-term use of opioids in pain management are not yet fully understood Yates, William R., MD “Somatoform Disorders.” eMedicine, November 20, 2003 (February 24, 2004) Resources American Academy of Neurology (AAN) 1080 Montreal Avenue, Saint Paul, MN 55116 (651) 695-2717 or (800) 879-1960; Fax: (651) 695-2791 memberservices@ aan.com American Academy of Pain Medicine (AAPM) 4700 West Lake, Glenview, IL 60025 (847) 375-4731; Fax: (877) 734-8750 aapm@amctec.com American Chronic Pain Association P O Box 850, Rocklin, CA 95677 (916) 632-3208 or (800) 533-3231 ACPA@ pacbell.net American Pain Foundation 201 North Charles Street, Suite 710, Baltimore, MD 21201-4111 (888) 615-PAIN International Association for the Study of Pain (IASP) Secretariat 909 NE 43rd Street, Suite 306, Seattle, WA 98105-6020 (206) 547-6409; Fax: (206) 547-1703 iaspdesk@juno.com NIH Neurological Institute P O Box 5801, Bethesda, MD 20824 (301) 496-5751 or (800) 352-9424 BOOKS Altman, Lawrence K., MD Who Goes First? The Story of SelfExperimentation in Medicine Berkeley, CA: University of California Press, 1998 American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision Washington, DC: American Psychiatric Association, 2000 Martin, John H Neuroanatomy: Text and Atlas, 3rd ed New York: McGraw-Hill, 2003 “Pain.” The Merck Manual of Diagnosis and Therapy, edited by Mark H Beers, MD, and Robert Berkow, MD Whitehouse Station, NJ: Merck Research Laboratories, 2002 Pelletier, Kenneth R., MD The Best Alternative Medicine, Part II, “CAM Therapies for Specific Conditions: Pain.” New York: Simon & Schuster, 2002 PERIODICALS Daitz, Ben “In Pain Clinic, Fruit, Candy and Relief.” New York Times, December 3, 2002 Duenwald, Mary “Tales from a Burn Unit: Agony, Friendship, Healing.” New York Times, March 18, 2003 Halsey, James H., MD “Atypical Facial Pain.” eMedicine, February 9, 2001 (February 24, 2004) Harstall, Christa, and Maria Ospina “How Prevalent Is Chronic Pain?” Pain: Clinical Updates 11 (June 2003): 1–4 Lasch, Kathryn E., PhD “Culture and Pain.” Pain: Clinical Updates 10 (December 2002): 1–11 Meier, Barry “The Delicate Balance of Pain and Addiction.” New York Times, November 25, 2003 Singh, Manish K., MD, Elizabeth Puscheck, MD, and Jashvant Patel, MD “Chronic Pelvic Pain.” eMedicine, November 7, 2003 (February 24, 2004) Wheeler, Anthony H., MD “Therapeutic Injections for Pain Management.” eMedicine, October 19, 2001 (February 24, 2004) http://www.emedicine.com/neuro/topic514.htm> Wheeler, Anthony H., MD, James R Stubbart, MD, and Brandi Hicks “Pathophysiology of Chronic Back Pain.” eMedicine, March 8, 2002 (February 24, 2004) 640 WEBSITES OTHER National Institute of Neurological Disorders and Stroke (NINDS) “Pain—Hope Through Research.” NIH Publication No 01-2406 2001 NINDS “Chronic Pain Information Page.” Bethesda, MD: NINDS, 2001 (February 24, 2004.) ORGANIZATIONS Rebecca J Frey, PhD S Pallidotomy Definition Pallidotomy is the destruction of a small portion of the brain within the globus pallidus internus, or GPi The GPi helps control voluntary movements Purpose Pallidotomy is performed to treat the symptoms of Parkinson’s disease (PD), which results from the death of cells in a part of the brain that controls movement, called the substantia nigra Part of the normal function of the substantia nigra is to inhibit overactivity of the GPi, which itself communicates with other portions of the brain in GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Early on in PD, symptoms can be effectively treated with medication, especially levodopa and the dopamine agonists (drugs that act like levodopa) As the disease progresses, increasing amounts of drugs are needed to control symptoms, and the patient’s response to the drugs declines Typically, within 10 years of starting treatment, the patient will develop uncontrolled movements, called dyskinesias, in response to drug treatment At this point, surgery is considered an option The GPi has two halves, which control movements on opposites sides of the body: right controls left, left controls right Unilateral (one-sided) pallidotomy may be used if symptoms are markedly worse on one side or the other, or if the risks from bilateral (two-sided) pallidotomy are judged to be too great Precautions Pallidotomy is major surgery on the brain It may cause excessive bleeding, and care must be taken in patients susceptible to uncontrolled bleeding or who are on anticoagulant therapy Description To destroy tissue in the GPi, a long needle-like probe is inserted deep into the brain, through a hole in the top of the skull To make sure the probe reaches its target exactly, a rigid “stereotactic frame” is attached to the patient’s head This provides an immobile three-dimensional coordinate system, which can be used both to determine the precise position of the GPi and to track the probe on its way to the target A single “burr hole” is made in the top of the skull for a unilateral pallidotomy; two holes are made for a bilateral procedure General anesthesia is not used for two reasons: first, the brain does not feel any pain; second, the patient must be awake and responsive in order to respond to the neurosurgical team as they monitor the placement of the probe The GPi is close to the nerve that carries visual information from the eyes to the rear of the brain Visual abnormalities during probe placement may indicate that it is too close to this region, and thus needs repositioning Other procedures may be used to ensure precise placement of the probe, including electrical recording and injection of a contrast dye into the spinal fluid The electrical recording can cause some minor odd sensations, but is harmless When the probe is in the correct position, its tip is heated briefly This destroys the surrounding tissue in an area about the size of a pearl If bilateral pallidotomy is being performed, the localizing and lesioning will be repeated on the other side Preparation A variety of medical tests are needed to properly locate the GPi and fit the frame These may include computed tomography (CT) scans, magnetic resonance imaging (MRI), and injection of dyes into the spinal fluid or ventricles (fluid-filled cavities) of the brain The frame is attached to the head on the day of surgery, which may be somewhat painful, although the pain is lessened by local anesthetic A mild sedative is given to ease anxiety Aftercare Pallidotomy takes several hours to perform In some medical centers, pallidotomy is performed as an outpatient procedure, and patients are sent home the same day Most centers provide an overnight stay or longer for observation and recuperation Movement usually improves immediately, and typically requires the reduction of medication to accommodate the improvement Risks Pallidotomy carries significant risks, especially in patients who are in poor health or who are cognitively impaired Brain hemorrhage is a possible complication, as is infection Damage to the optic tract, which carries visual messages from the eye to the brain, is a small but significant risk, and is more significant in bilateral pallidotomy Speech impairments may also occur, including difficulty retrieving words, and slurred speech All PD experts agree that risks are lowest when the surgery is performed by neurosurgeons with the most experience in the procedure Among the best surgeons, the risk of serious morbidity or mortality (i.e., serious consequences or death) is 1–2% Hemorrhage may occur in 2–6%, visual deficits in 0–6%, and weakness in 2–8% Normal results Pallidotomy improves the patient’s ability to move, especially between levodopa doses (so-called “off” periods) Studies show the surgery generally improves tremor, rigidity, and slowed movements by 25–60% Dyskinesias typically improve by 75% or more Improvements from unilateral pallidotomy are primarily on the side opposite the surgery Balance does not improve, nor “nonmotor” symptoms such as drooling, constipation, and orthostatic hypotension (lightheadness on standing) GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 641 Pallidotomy complex control circuits In PD, the overactivity of the GPi is in part responsible for the slowed movements, tremor, and rigidity that are the classic symptoms of the disease By destroying part of the GPi, some balance is restored to these movement-control circuits, allowing faster and more fluid movements Pantothenate kinase-associated neurodegeneration Resources Key Terms BOOKS Jahanshahi, M., and C D Marsden Parkinson’s Disease: A Self-Help Guide New York: Demos Medical Press, 2000 WEBSITES Dystonia Painful involuntary muscle cramps or spasms National Parkinson’s Disease Foundation (March 23, 2004) WE MOVE (March 23, 2004) Enzyme A protein that catalyzes a biochemical reaction without changing its own structure or function Richard Robinson S Pantothenate kinase- associated neurodegeneration Definition Pantothenate kinase-associated neurodegeneration (PKAN), long known as Hallervorden-Spatz syndrome (HSS), is a very rare childhood neurodegenerative disorder that is associated with the accumulation of iron in the brain, which causes progressively worsening abnormal movements and dementia Description In addition to its original name, Hallervorden-Spatz syndrome, pantothenate kinase-associated neurodegeneration has also been called neurodegeneration with brain iron accumulation (NBIA) The name HallervordenSpatz is rapidly being discontinued by those who study and treat the disease, both because the new names indicate the nature of the underlying disorder, and because Julius Hallervorden, who described the syndrome, was involved in a “selective euthanasia” program in Nazi Germany to kill retarded children Neurodegeneration The deterioration of nerve tissues brain cells It is not yet known how this leads to the disease, but it is possible that cysteine interacts with iron, leading to buildup of other molecules within brain cells that puts stress on the cells and causes them to degenerate PKAN causes dystonia, a sustained posturing of lower limbs due to excessive muscle contraction Leg dystonia leads to gait difficulties and other limitations of movement Dystonia may also affect the upper limbs and the muscles of the face and neck Abnormal movements may also include writhing or tremor Ability to walk is usually lost within 15 years Dysarthria, or impairment of the ability to speak, is common, and is usually accompanied by swallowing difficulty PKAN also causes progressive dementia, or impairment of normal intellectual function, although this is more variable among patients PKAN may also cause a degenerative eye condition, retinitis pigmentosa An atypical form of PKAN has similar features, but with later age of onset and more variable and less severe symptoms Speech difficulties tend to be more common in atypical patients Atypical patients may or may not have a recognizable gene defect Diagnosis Demographics PKAN is so rare that there is no reliable information on its prevalence It affects boys and girls equally Typical age of onset is in middle childhood to early adolescence, although onset in early adulthood may occur Treatment team Causes and symptoms PKAN occurs due to mutation in the gene for pantothenate kinase (PANK2), which is an enzyme, a type of protein that regulates a reaction inside a cell PANK2 helps regulates the production of coenzyme A, an important intermediate in the production of energy within all cells Mutations in the gene for PANK2 lead to loss of function of this enzyme, the consequence of which is accumulation of iron and the amino acid cysteine within 642 Diagnosis of PKAN begins with a neurological exam, which is followed up by a magnetic resonance imaging (MRI) scan to reveal a characteristic signal from the affected portions of the brain Genetic testing may be done to look for the mutation in the PKAN gene Treatment involves a pediatric neurologist, a speechlanguage pathologist, and physical and occupational therapists Treatment There is no treatment that can halt or slow the degeneration of the brain that occurs in PKAN The recent discovery of the gene defect may lead to a better GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Drug therapy for the movement disorders of PKAN is variably successful, and becomes less so with time Drugs used for Parkinson’s disease such as levodopa may be beneficial in some patients Trihexyphenidyl may be useful Oral antispasticity medications, including diazepam and dantrolene, can help reduce muscle stiffness and spasticity Intrathecal baclofen has been successful in several patients A pallidotomy, a type of brain surgery that destroys part of the globus pallidus internus, a structure in the brain that regulates movements, has shown some success at relieving painful dystonia and returning some function to the affected limbs Speech impairment may be the most severe consequence of PKAN Assistive communication devices such as computers or letter boards offer the possibility of continued communication even as the disease worsens Recovery and rehabilitation Clinical trials PKAN is so rare there are few clinical trials Some effort is underway to determine whether supplements with PANK2’s normal products or related molecules may be effective Description Paramyotonia congenita is passed on in families as an autosomal dominant trait This means that males and females are affected equally; it also means that if one parent has the trait, the offspring have a 75% chance of also having the condition Demographics Paramyotonia congenita is present from birth on In some cases, the symptoms appear to grow more mild as the patient ages Causes and symptoms Paramyotonia congenita is believed to be caused by a defect in the chloride channels of the muscles As a result, the relaxation phase of the muscles is impaired, resulting in prolonged muscle contraction and stiffness This “overuse” of the muscle results in the muscle becoming enlarged and bulky (called muscle hypertrophy) Symptoms of paramyotonia congenita include stiffness and enlargement of various muscle groups, particularly those in the legs The muscle stiffness of paramyotonia congenita is often exacerbated by cold temperatures and inactivity and relieved by warmth and exercise Diagnosis Prognosis The average duration of disease is 11 years Death is usually caused by aspiration pneumonia, brought on by food inhaled into the airways Resources BOOKS The Official Patient’s Sourcebook on Hallervorden-Spatz Disease: A Revised and Updated Directory for the Internet Age San Diego: Icon Health Publications, 2002 WEBSITES NBIA Disorders Association (April 27, 2004) Electromyographic (EMG) testing involves placing a needle electrode into a muscle and measuring its electrical activity EMG testing in paramyotonia congenita may reveal differences between electrical activity in a warm muscle and electrical activity in a cooled muscle There are a number of genetic defects that are associated with the chloride channel defect of paramyotonia congenita, some of which can be revealed through genetic testing Treatment team Paramyotonia congenita is diagnosed and treated by neurologists Treatment Richard Robinson Papilledema see Visual disturbances S Paramyotonia congenita Definition Paramyotonia congenita is an inherited condition that causes stiffness and enlargement of muscles, particularly leg muscles Paramyotonia congenita is usually mild enough not to require any treatment at all If muscle stiffness is truly problematic, quinine or anticonvulsant medications (such as phenytoin) may improve functioning Prognosis Paramyotonia congenita has an excellent prognosis Although annoying, it does not cause significant disability, and the patient usually learns to make lifestyle adjustments that prevent exacerbations (for example, dressing warmly and avoiding exposure to cold) GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 643 Paramyotonia congenita understanding of the neurodegenerative process, and thereby to better treatments Paraneoplastic syndromes Resources that the patient may have a hidden cancer and that neurological symptoms could be paraneoplastic Symptoms include fatigue, weakness, muscular pain in upper arms, difficulty walking, burning, numbness or tingling sensations in the limbs (peripheral paresthesia), dry mouth, sexual function difficulty, and drooping eyelids BOOKS Brown, Robert H., and Jerry R Mendell “Muscular Dystrophies and Other Muscle Diseases.” In Harrison’s Principles of Internal Medicine, edited by Eugene Braunwald, et al NY: McGraw-Hill Professional, 2001 Rose, Michael, and Robert C Griggs “Hereditary Nondegenerative Neuromuscular Disease.” In Textbook of Clinical Neurology, edited by Christopher G Goetz Philadelphia: W B Saunders Company, 2003 WEBSITES National Institute of Neurological Disorders and Stroke (NINDS) NINDS Myotonia Congenita Information Page November 8, 2001 (June 3, 2004) Rosalyn Carson-DeWitt, MD Neurological signs may include dementia with or without brain stem signs, rapid and irregular eye movements, and ophthalmoplegia (weakness or paralysis in muscles that move the eye) Paraneoplastic syndromes involving the nervous system include: Lambert-Eaton myasthenic syndrome (LEMS), stiff person syndrome (SPS), encephalomyelitis (inflammation of the brain and spinal cord), myasthenia gravis (MG), cerebellar degeneration (CD), limbic and/or brain stem encephalitis, neuromyotonia, opsoclonus myoclonus (OM), and sensory neuropathy Demographics S Paraneoplastic syndromes Definition Paraneoplastic syndromes (PS) are rare disorders triggered by the immune system’s response to cancer cells, or by remote effects of tumor-derived factors These syndromes are believed to occur when cancer-fighting antibodies or white blood cells, known as T-cells, mistakenly attack normal body cells These disorders typically affect middle-aged to older people and are most common in patients with lung, ovarian, lymphatic, or breast cancer Description Paraneoplastic syndromes are defined as clinical syndromes involving non-cancerous effects in the body that accompany malignant disease, and can affect any part of the nervous system from the cerebral cortex to peripheral nerves and muscles In a broad sense, these syndromes are collections of symptoms that result from substances produced by the tumor, occurring far away from the tumor itself When a tumor arises, the body may produce antibodies to fight it, by binding to and helping in the destruction of tumor cells Unfortunately, in some cases, these antibodies cross-react with normal tissues and destroy them, which may stimulate the onset of PS However, not all PS are associated with such antibodies Neurological symptoms generally develop over a period of days to weeks, and usually occur prior to the discovery of cancer, which can complicate diagnosis In these cases, additional information should raise the possibility 644 Most paraneoplastic syndromes are rare, affecting less than 1% of persons with cancer Exceptions include LEMS, which affects about 3% of patients with small-cell lung cancer; MG, which affects about 15% of persons with thymoma; and demyelinating peripheral neuropathy, which affects about 50% of patients with the rare osteosclerotic form of plasmacytoma No race, age, or sex preference has been reported Causes and symptoms Most or all paraneoplastic syndromes are activated by the body’s immune system In response to a tumor, the immune system produces an antigen that is normally expressed exclusively in the nervous system The tumor antigen is identical to the normal antigen, but for unknown reasons the immune system identifies it as foreign and mounts an immune response In general (although not always), PS develops in an acute or subacute fashion, over days or weeks Symptoms may include difficulty in walking and/or swallowing, loss of muscle tone, loss of fine motor coordination, slurred speech, memory loss, vision problems, sleep disturbances, dementia, seizures, sensory loss in the limbs, and vertigo The nervous system disability is usually severe Diagnosis Currently, paraneoplastic syndromes are diagnosed using two different technologies in testing blood Blood testing with western blot using recombinant human antigens is a highly specific method; it can clearly distinguish between different paraneoplastic antibodies Immunohistochemistry can detect paraneoplastic antibodies in blood GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Antibodies A protein produced by the body’s immune system to fight infection or harmful foreign substances Cytotoxic T-cells A type of white blood cells, T lymphocytes, that can kill body cells infected by viruses or transformed by cancer Dysarthria Problems with speaking caused by difficulty moving or coordinating the muscles needed for speech Nystagmus Rapid, involuntary eye movements Ophthalmoplegia Drooping eyelids serum, providing a general diagnosis, but cannot distinguish between the different PS antibodies The physician should search for cancer using the most sensitive technology available, including magnetic resonance imaging (MRI) and a fluorodeoxyglucose body positron emission tomography (PET) scan Treatment team Due to the many manifestations of paraneoplastic syndromes, PS should be evaluated clinically by a coordinated team of doctors, including medical oncologists, surgeons, radiation oncologists, endocrinologists, hematologists, neurologists, and dermatologists Treatment Because PS are considered to be immune-mediated disorders, two treatment approaches have been used: removal of the source of the antigen by treatment of the underlying tumor, and suppression of the immune response For many PS, the first approach is the only effective treatment In the LEMS and MG, plasma exchange or intravenous immune globulin is usually effective in suppressing the immune response Physicians often also prescribe a combination of either plasma exchange or intravenous immune globulin and immunosuppressive agents such as corticosteroids, cyclophosphamide, or tacrolimus For most paraneoplastic syndromes, immunotherapy is not effective Recovery and rehabilitation Some disorders such as the LEMS and MG respond well to immunosuppressant drugs and to treatment of the underlying tumor The peripheral neuropathy associated Clinical trials As of mid-2004, the numerous clinical trials recruiting participants for the study and treatment of paraneoplastic syndromes include: • Interferon and Octreotide to Treat Zollinger-Ellison Syndrome and Advanced Non-B Islet Cell Cancer • Evaluating Pancreatic Tumors in Patients with ZollingerEllison Syndrome • Treatment of Zollinger-Ellison Syndrome • The Use of Oral Omeprazole and Intravenous Pantoprazole in Patients with Hypersecretion of Gastric Acid Updates information on these and other ongoing trials can be found at the National Institutes of Health website for clinical trials at Prognosis The prognosis for persons with paraneoplastic syndromes depends on the specific type of PS, and the progression of the underlying cancer LEMS and MG are neuromuscular junction diseases, which can recover function once the causal insult is removed, because there is no neuronal loss Disorders such as CD are usually associated with neuronal damage, and because they evolve subacutely and treatment is often delayed, neurons die, making recovery much more difficult Some central nervous system disorders such as OM may not involve cellular loss and, thus, patients with these disorders, like those with LEMS, have the potential for recovery Special concerns It is important that caregivers for those with paraneoplastic syndromes receive adequate support The disorder typically emerges suddenly and without warning The neurological manifestations of PS are complex and often require 24-hour patient care Many caregivers will require quick access to information on caring for a disabled person This includes information on social security benefits, insurance coverage, handicapped license plates, evaluations for physical therapy; medical equipment such as hospital beds, ultra-light wheelchairs, handheld showerheads, GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 645 Paraneoplastic syndromes Key Terms with osteosclerotic myeloma generally resolves when the tumor is treated with radiotherapy A few disorders may respond to treatment of the underlying tumor, immunosuppression, or both, or they may resolve spontaneously In many instances, it is not clear whether the PS resolve spontaneously or in response to treatment Disorders involving the central nervous system, such as encephalomyelitis associated with cancer or paraneoplastic cerebellar degeneration, usually respond poorly to treatment, although they may stabilize when the underlying tumor is treated Parkinson’s disease and home healthcare and visiting nurses; and social workers and other support services normal control of movement, causing the person to experience slowed movements, stiffness or rigidity, and tremor Resources BOOKS Demographics Ruter, U., et al Paraneoplastic Syndromes Basel: S Karger Publishing, 1998 PERIODICALS Robert, B D., and P B Jerome “Paraneoplastic Syndromes Involving the Nervous System.” New England Journal of Medicine 349 (2003): 1543–1554 Sutton, I., and J B Winer “The Immunopathogenesis of Paraneoplastic Neurological Syndromes.” Clinical Science 102 (2002): 475–486 PD is one of the most common neurodegenerative diseases, second only to Alzheimer’s disease in the number of people affected Estimates suggest that approximately 750,000 Americans have PD It affects older people much more than younger, and indeed, old age is the single greatest risk factor for PD The average age at diagnosis is 62 Onset before age 40 is extremely rare Men are slightly more likely to be affected than women OTHER “NINDS Paraneoplastic Syndromes Information Page.” National Institute of Neurological Disorders and Stroke May 1, 2004 (June 2, 2004) Santacroce, Luigi “Paraneoplastic Syndromes.” eMedicine May 1, 2004 (June 2, 2004) ORGANIZATIONS American Autoimmune Related Diseases Association 22100 Gratiot Avenue, Eastpointe, MI 48201-2227 (586) 776-3900 or (800) 598-4668; Fax: (586) 776-3903 aarda@aol.com National Cancer Institute (NCI)—National Institutes of Health Bldg 31, Rm 10A31, Bethesda, MD 20892-2580 (301) 435-3848 cancermail@icicc.nci.nih.gov American Cancer Society 1599 Clifton Road, NE, Atlanta, GA 30329-4251 or (800) ACS-2345 (227-2345) Francisco de Paula Careta Iuri Drumond Louro, MD, PhD S Parkinson’s disease Definition Parkinson’s disease (PD) is a neurodegenerative disorder that causes slowed movements, tremor, rigidity, and a wide variety of other symptoms “Neurodegenerative” refers to the degeneration, or death, of neurons, the type of cell in the brain that is the basis for all brain activity Description Parkinson’s disease occurs when neurons (nerve cells) in a part of the brain called the substantia nigra degenerate, or die off The loss of these cells disrupts the brain’s 646 Causes and symptoms In the vast majority of cases, the cause of PD is unknown Besides old age, there are several well-recognized risk factors These include exposure to pesticides or herbicides, rural living, and drinking well water Because of this, it is assumed that some type of environmental pollutant, either a pesticide or something associated with its use, is involved in causing PD Other known risk factors include welding and exposure to manganese, further strengthening the case for an environmental toxin There is also evidence that genes play an important role in determining the risk of PD PD can run in families, affecting members of the family at a much higher rate than expected by chance alone Among identical twins, the situation is complex: if one twin develops the disease early, the other is more likely to as well; but if one twin has typical late-onset PD, the other is no more likely to develop the disease than would be expected by chance Several genes have been identified that cause PD in some people, but the number of people affected by these genes is quite small Therefore, the interest of these genes is more in what they can reveal about the disease process than in providing the solution to the mystery of what causes PD in most people Two of the genetic mutations identified involve a protein called alpha-synuclein, whose normal function is unknown It is believed that the mutations prevent the normal breakdown of alpha-synuclein, leading it to accumulate in the neuron, where it then goes on to damage the cell Another gene mutation that causes PD affects a protein called parkin, which normally helps break down proteins It is believed that the loss of parkin causes build-up of proteins (though not of alpha-synuclein), again leading to damage Researchers believe that environmental toxins may also cause similar problems, and it now seems likely that problems in protein breakdown are a significant step leading to PD, whether of genetic or environmental causation Finally, a combination of genetic and environmental factors is likely to be important GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Whatever the ultimate cause, people with PD share the same pathology, or disease process, in their brains The symptoms of PD arise when cells in the substantia nigra (SN) degenerate The SN is located at the base of the brain, near the top of the spinal column Neurons of the SN receive messages from, and send messages to, several other portions of the brain, all of which are involved in the control of movement By interacting with these other regions, the SN helps to ensure that movements will be smooth, fluid, and controlled SN cells communicate with other cells by releasing the chemical dopamine Dopamine released by SN cells stimulates cells in other brain regions to act As SN cells die, they release less dopamine, and the receiving cells are not stimulated as much This leads to the disordered movement of PD The SN is also involved in regulating numerous other types of brain behaviors, and late-stage PD is marked by a wide variety of symptoms that probably reflect loss of this regulation The earliest symptoms of PD, and the most widely recognized, are tremor, slowed movements (bradykinesia), and stiffness or rigidity Symptoms often begin on one side of the body, and progress over time to involve both sides The tremor of PD is a rest tremor—the shaking occurs when the patient is not trying to use the limb, and diminishes when the limb is in use Bradykinesia and stiffness, along with loss of some balance reflexes, can combine to cause postural instability, and increase the likelihood of falling down Other symptoms of PD include: • orthostatic hypotension, or loss of blood pressure upon standing, which can cause dizziness and fainting • painful foot cramps • micrographia, or reduced size of handwriting • reduced voice volume • reduced facial expression • panic attacks • late-stage dementia Diagnosis Parkinson’s disease is diagnosed by a careful neurological examination, testing movements, coordination, reflexes, and other aspects of function If the physician suspects PD, the patient will usually be referred to a neurologist for definitive diagnosis Unilateral (one-sided) tremor, slowed movements, and muscle stiffness are generally enough to confirm the diagnosis; two of the three are usually considered definitive Several specialized tests may be used, including imaging of the brain with magnetic resonance imaging (MRI) or positron emission tomography (PET) These are not essential to diagnosis in most cases, but may help to confirm the diagnosis in difficult cases and to distinguish PD from similar diseases such as progressive supranuclear palsy, corticobasal degeneration, or multiple system atrophy Clues that the disease is one of these, rather than PD, include early or rapidly progressing dementia, loss of coordination, or early and prominent orthostatic hypotension (lightheadedness upon standing) Certain medications can cause a PD-like syndrome, and it is important to rule these out These drugs include certain antipsychotic medications (haloperidol) and antivomiting drugs (metoclopramide) Treatment team Treatment of PD is headed by a neurologist, who may be either a general neurologist or a movement disorders specialist The movement disorders specialist is most likely to be aware of the most current trends in treatment Since PD therapy continues to undergo rapid advances, it may be an advantage to see a specialist when possible Other team members may include a speech/language pathologist for addressing voice and swallowing disorders, a geriatric medicine specialist to coordinate other medical and social issues, a neuropsychologist for expertise on cognitive aspects of PD and its treatment, and a neurosurgeon • excessive sweating Treatment • constipation • decreased ability to smell • male impotence • drooling • sleep disturbance • depression • anxiety There are no treatments that have been proven to slow the course of PD, although research published in 2003 suggested that coenzyme Q10 may offer a slight benefit in this regard The study has not been replicated, and its authors noted it would be premature to recommend treatment with this very expensive supplement Additional claims have been made that two medications used to treat PD symptoms—selegiline and dopamine agonists—may have GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 647 Parkinson’s disease in most cases For instance, a person with a genetically weaker ability to dispose of proteins, who was also exposed to pesticides, might develop PD, whereas a person with different genes but the same exposure might not Parkinson’s disease The highlight indicates the area of the brain affected by Parkinson disease (David Gifford / Photo Researchers, Inc.) some disease-slowing effects These claims are not widely accepted The treatment of the symptoms of PD is complex for several reasons First, PD is a progressive disease, getting worse over time, so that the medications and doses that work well early in the disease are insufficient later on Second, the most effective drugs have long-term side effects that are troubling and difficult to control Third, there are a lot of different treatment options, and finding the right combination can be time consuming Fourth, the PD patient is likely being treated for other conditions associated with advancing age, and these conditions or their treatment may interfere with treatment of PD Finally, a major treatment option for late-stage PD is surgery, but the risks of surgery are significant, and determining when and what kind of surgery to perform is a complicated decision Once the diagnosis of PD has been made, a central question is when to begin treatment Treatment is typically not started right away (unless the patient elects to use coenzyme Q10), but instead is delayed until symptoms begin to interfere with his or her ability to work or engage in activities of daily living This may be a year or even more after diagnosis 648 Key Terms Neurodegenerative Relating to the deterioration of nerve tissues Drug treatment The next question is what drug to begin with The most powerful treatment for the symptoms of PD is levodopa, which is taken into the brain and substitutes for the dopamine no longer being made by the substantia nigra Similar in effect are the dopamine agonists, which mimic the effect of dopamine on the cells that normally receive dopamine from the SN Three other medications also commonly used in PD, whose effects are not nearly as strong as either levodopa or the dopamine agonists, are anticholinergics, selegiline, and amantadine These are often prescribed early on, when symptoms are not severe, saving the more powerful medications for later on Anticholinergics include benztropine and trihexyphenidyl The loss of SN activity means that another GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS Selegiline inhibits the action of monoamine oxidase B, an enzyme in the brain that breaks down dopamine Thus, selegiline prolongs the activity of dopamine in the brain It can cause insomnia and hallucinations, as well as orthostatic hypotension It may also interact with certain types of antidepressants, and for this reason, selegiline may be discontinued when beginning treatment for depression In the early 1990s, selegiline was examined for its potential for neuroprotection, or disease slowing The results of that trial were inconclusive; selegiline had such a significant and long-lasting symptomatic benefit that it was difficult to examine its disease-slowing effects independently Amantadine improves PD symptoms through an unknown mechanism It is beneficial for each of the major movement symptoms of PD, although its effects are not strong It also can lessen dyskinesias, which are unwanted movements that develop late in PD due to treatment Amantadine can cause orthostatic hypotension and confusion Most drugs have side effects, and drugs for PD are no exception The most effective drugs for PD, levodopa and the dopamine agonists, cause a set of side effects called “dopaminergic” side effects, indicating they derive from mimicking the action of dopamine Dopaminergic side effects include nausea and vomiting, orthostatic hypotension, excessive sleepiness, hallucinations, and dyskinesias (in more advanced patients) Nausea, vomiting, and orthostatic hypotension tend to lessen with use, and not pose long-term problems for most patients Excessive sleepiness is a problem for many patients Dyskinesias are an unavoidable effect of dopaminergic treatments, although dopamine agonists tend to cause less of it than levodopa Dyskinesias tend to appear after three or more years of successful treatment, and become worse over time Episodes of dyskinesias can be lessened by reducing the dose of the dopaminergic drug, but may lose symptomatic benefit Adjusting drugs to minimize dyskinesias while maintaining good symptom control is a central challenge of managing PD Levodopa is the most effective treatment for PD symptoms, and is the drug used most often at the beginning of disease in elderly patients, because it is less likely to cause hallucinations than dopamine agonists It is given in a pill that also contains another medication, called carbidopa, which inhibits an enzyme that would act on dopamine in the bloodstream, thus allowing more of it to reach the brain In order for levodopa to be taken up by the gut and to pass from the bloodstream to the brain, a carrier that also moves amino acids from food must transport the drug For this reason, doctors typically suggest that patients avoid taking levodopa with or right after a proteinrich meal Levodopa may also be given with another medication, called a COMT inhibitor, which further prevents its breakdown in the bloodstream A new pill combines levodopa, carbidopa, and a COMT inhibitor Dopamine agonists are almost as effective as levodopa for combating PD symptoms, and have the advantage that their use does not lead to dyskinesias as frequently as levodopa does For this reason, many movement disorder specialists begin their patients on a dopamine agonist rather than levodopa This is especially true for younger patients, who can anticipate more years of dopaminergic therapy, and a higher likelihood of developing dyskinesias as a result There are four major dopamine agonists available in the United States: pergolide, pramipexole, bromocriptine, and ropinirole Each is taken as a pill, and can be taken alone or in combination with levodopa or other medications Some patients respond better to one than another, and inadequate relief from one does not mean the same should be expected from another The U.S Food and Drug Administration was expected to approve a fifth dopamine agonist, called apomorphine, by mid-2004 Unlike the others, it is injected, and provides very rapid, short-term symptomatic relief when a dose of levodopa wears off Excessive sleepiness is a potentially dangerous side effect for all the dopaminergic drugs (levodopa and the dopamine agonists) This can take the form of predictable, peak-dose sleepiness, or general increase in sleepiness during the day, or a sudden, unpredictable “attack” of sleepiness and falling asleep The latter can be dangerous if it occurs while driving or performing another activity requiring full awareness Patients are cautioned to be aware of changes in sleepiness especially after changing a medication, and to avoid driving whenever possible if excessive sleepiness does become a side effect issue Complications of advanced disease After several years of successful treatment, most patients begin to develop one or more motor complications These often begin with “wearing off,” a reduction in the duration of effect of a given dose of levodopa, which initially can be countered by dosing more frequently Another complication is “on-off,” in which the symptomatic benefit of a given dose suddenly switches off and the patient becomes rigid, with tremor and slowed movements emerging When this occurs at home, the patient will typically just take another dose of medication, and wait for it GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS 649 Parkinson’s disease brain system that controls movement, the cholinergic system, is relatively overactive Anticholinergics dampen the activity of this system, restoring some balance to the control of movement Anticholinergics are usually well tolerated in younger patients, but their side effects can be a significant barrier to their use in the elderly Side effects include sedation, confusion, hallucinations, delirium, dry mouth, constipation, and urinary retention Parkinson’s disease to begin to work It is more of a problem when it occurs while the patient is out and about, and frequent on-off episodes may make the patient reluctant to leave the home Apomorphine injection may be useful in this situation, since it works very rapidly (approximately seven minutes), and can therefore be used as a “rescue” for sudden off periods Dyskinesias are a third motor complication Dyskinesias are uncontrolled writhing movements that typically occur at the peak of effect of a levodopa dose In some cases for some patients, dyskinesias are mild enough that they are not problematic In other cases, they interfere with function, and attempting to reduce them becomes an important treatment issue While drug adjustments can have some effect, as the disease progresses it becomes more and more difficult to maintain adequate symptom control while avoiding dyskinesias At this stage, the patient may consider surgery for treatment of PD symptoms Other complications arise in advanced PD, especially in “non-motor” symptoms, those that not affect movement Low voice volume may be amenable to speech therapy treatment, with one of the most effective programs being Lee Silverman voice treatment, which focuses on conscious attempts to increase volume Orthostatic hypotension may be treatable with increased salt intake, compression stockings, and medication Drooling may become an issue in later-stage disease; there are both drug treatments and non-drug therapies available to reduce this problem Constipation is a significant problem for many advanced PD patients, and can be treated with standard measures such as increasing the fiber in the diet and bulking laxatives Panic attacks and anxiety are common in PD These can be addressed both through helping the patient understand that this is a feature of the disease, and through antianxiety medication Depression affects many PD patients, and can worsen other aspects of the disease It usually responds well to antidepressant medications Dementia (loss of memory and impairment of other thinking functions) occurs more frequently in PD patients than in the population at large Treatment is similar to that in nonPD patients, although some medications cannot be used because they have undesirable side effects for PD patients Psychosis-hallucinations, paranoia, nightmares, and delusions may be a response to dopaminergic medications If these side effects cannot be controlled through modification of treatments, an antipsychotic drug may be useful Surgery Brain surgery is a treatment option in late-stage PD The best candidate is the individual who continues to respond to levodopa, but whose treatment is complicated by unacceptable dyskinesias even after medication adjustment Dementia or other significant health-related conditions may make the patient unsuitable for the rigors of 650 surgery The patient is usually evaluated by the neurologist, a neuropsychologist, and a neurosurgeon before deciding whether surgery is the right option There are two types of surgery for PD An “ablative” lesion destroys a small portion of the brain, and in so doing, restores the balance of neural activity within the movement control circuits of the brain; ablation means to destroy or remove The second option is deep brain stimulation (DBS), which accomplishes the same thing by implanting an electrode in the target brain region; electrical pulses shut the region down Ablative lesions are simpler and less prone to long-term complications, but they are not adjustable after the lesion has been made DBS is more complex, expensive, and time consuming, and carries a significant risk for infection or equipment malfunction, but it can be adjusted to more precisely target the brain region, thereby enhancing the surgical effect Three brain regions are targeted in PD surgery Ablation of the thalamus (thalamotomy) is primarily effective in controlling tremor, and is not widely performed anymore since other, more effective targets are available The globus pallidus internus (GPi) can either be ablated (pallidotomy) or stimulated (GPi DBS), which is effective for all the major motor symptoms of PD (tremor, bradykinesia, rigidity), and can improve them by 25–60% It is also effective for reducing dyskinesias by up to 90% The subthalamic nucleus can be stimulated in STN DBS, and is highly effective for all the major motor symptoms and dyskinesias, to a somewhat greater extent than GPi DBS An additional advantage of STN DBS is that it is safer to on both sides of the brain (left and right, termed bilateral) than GPi DBS Therefore, if the patient is affected by disabling symptoms on both sides, as is often the case in advanced PD, bilateral STN DBS may be a better choice Clinical trials Parkinson’s disease is the subject of intense research, and there are usually several large and important clinical trials going on at any time Trials may focus on slowing the disease, determining the best drug treatment, or refining surgical methods and targets Two experimental forms of surgery have been the subject of recent clinical trials The first is the implantation of cells into the substantia nigra to replace the lost dopamine-producing cells The implanted cells come from fetal tissue Fetal-tissue transplants have led to success, but also to uncontrolled dyskinesias in some patients For this reason, such trials on are on hold until a better understanding of this problem is discovered and methods are developed to avoid it The second form of surgery delivers a growth factor to the substantia nigra via an implanted pump and tube GALE ENCYCLOPEDIA OF NEUROLOGICAL DISORDERS ... Washington, DC 20 0 0 2- 424 2 (20 2) 33 6-6 0 13; Fax: (20 2) 21 8 -3 599 kcooke@apa.org Dawn Cardeiro, MS, CGC S Neurosarcoidosis Central nervous system (CNS) involvement can affect the pituitary... Bethesda, MD 20 8 92 (30 1) 49 6-5 751 or (800) 3 5 2- 9 424 National Organization for Rare Disorders 55 Kenosia Avenue, Danbury, CT 0681 3- 1 968 (20 3) 74 4-0 100 or (800) 99966 73; ... (800) 59 8-4 668; Fax: (586) 77 6 -3 9 03 aarda@aol.com National Cancer Institute (NCI)—National Institutes of Health Bldg 31 , Rm 10A31, Bethesda, MD 20 8 9 2- 2580 (30 1) 43 5 -3 848 cancermail@icicc.nci.nih.gov